The activity or effectiveness of hair shaping preparations is based mainly on the inclusion therein of an agent for softening and relaxing the keratin protein present in hair by reducing the disulfide linkages of keratin. The hair fiber is wound on rods to achieve the desired waving effect or manipulated into a straightened condition and allowed to remain wetted with the reducing lotion for a desired period, after which the reducing lotion is rinsed off and finally oxidized with a neutralizing solution or air oxidized.
Basically, hair is softened and swelled by rupture of disulfide bonds present in the cysteine component of keratin by the use of a mild alkaline reducing agent. Cleavage of at least some of the disulfide bonding to form the corresponding cysteine residue is necessary to allow for molecular rearrangement which takes place during the hair fiber molding operation. The reductive fission of hair disulfides generally causes reddening of the scalp area and damage to the hair fiber, particularly hair which has been bleached, tinted or otherwise damaged. Current hair structure altering lotions which provide relaxation of imposed stress include aqueous solutions of alkaline mercapto compounds, sulfites or bisulfites at a pH of between 7 and 9.5. In order to obtain a permanent effect, particularly in hair straightening, it is often necessary to introduce the active agent in relatively high concentration with the result that the reducing lotion is provided at almost the limit of its physiological compatibility or tolerability.
Damage to hair is increased where heat waving, as opposed to cold waving, is employed. Of the reducing agents currently in use, the thioglycolates or thioglycolic acid, dithioglycolic acid and mercapto compounds such as ammonium thioglycolate, glyceryl, monothioglycolate, mercapto propionic acid and mercapto ethyl amine are most often employed in professional waving or hair straightening. Alkaline sulfites and bisulfites are generally reserved for home permanent use. In addition to the reducing agent, alkalis having a dissociation constant less than 5.times.10.sup.-3, are also used to facilitate diffusion through the hair. These promotors include ammonia, ammonium hydroxide, ethanol amine, diisopropanol amine, glycine, and lysine.
In an attempt to minimize these harmful effects polymeric quaternized amines have been developed as reducing agent supports, e.g. see U.S. Pat. No. 4,579,732. These basic compounds have not been found to be completely satisfactory for the reason that they react with anionic components which are often present in hair structure altering compositions. Additionally the terminal amino groups react with hydrogen peroxide to form nitrogen oxides, thus increasing the effective amounts of peroxide which must be employed in fixing solutions. Since peroxides are known to have a hair drying effect, it is desirable to maintain the peroxide at a minimum level. In addition the large molecular size of these polymeric products prevents their penetration into the hair fiber and instead forms a coating over the hair which is subject to tack under conditions of high humidity. Further, many reducing lotions produce a disagreeable odor during reduction of the cysteine molecule which the polymeric amines are unable to overcome. Finally, the relatively high viscosity of these quaternized polymers together with the normal variations in molecular weight in the polymer chains in the product lead to formulation problems in reproducibility of product quality and in storage of the product over extended periods.
All of the commercial reducing lotions cause some degree of hair damage depending on the tightness and thickness of the curl, the temperature of processing, the concentration of the alkaline reducing agent and the condition of the hair. Accordingly, the art continues to seek means and possibilities whereby to provide for the aforesaid waving and straightening lotions, compositions which are less damaging to the skin and hair and which contain stable components simple to incorporate into the standard reducing lotions currently in use so as to provide the same or more effective results for heat or cold permanent waving and hair straightening. One method for the realization of these objects can be achieved by promoting penetration of the reducing lotion and providing absorption at a faster rate so that the time hair fiber is exposed to chemical action is reduced.
Secondary aims for permanent waving compositions include masking the thiol odor of the reducing lotion, providing non-degradable compounds which may be easily and reproduceably formulated and minimizing skin irritation caused by routine exposure of professional hair dressers or erythema on the scalp and neck of the subject undergoing treatment.
Accordingly, it is an object of this invention to achieve the various aims enumerated above by a simple and commercially feasible process involving the addition of the compound of the present invention as a component in standard hair structure and configuration altering lotions used both professionally and at home.
Another object of the invention is to provide an additive to hair reducing lotions which promotes a higher degree of curl in a shorter period of time.
Another object of the invention is to provide an additive which actually conditions the hair undergoing restructuring treatment.
Another object is to provide a compound which, when added to a hair waving or straightening lotion, increases the penetration rate of the lotion to minimize run-off and dripping.
Yet another object is to provide a long lasting hair permanent that moisturizes and protects the hair fiber so as to give the processed hair a silky softness.
Still another object is to provide an additive which improves hard water solubility of components in the neutralizing lotion.
Still another object is to provide a non-polymeric compound of reproduceable composition which is substantially non-reactive with respect to anionic components and hydrogen peroxide.
These and other objects of the invention will become apparent from the following description and disclosure.